Characteristics of a Measles Outbreak in a Pediatric Hospital in the Honam Region, 2025

In March 2025, a measles outbreak was reported at A Children's Hospital in the Honam region, triggered by an unvaccinated child who had recently traveled to Vietnam. This study describes the epidemiological characteristics, transmission dynamics, and immunity status of healthcare workers, providing evidence for the future prevention of hospital-based measles transmission.

According to the Korea Disease Control and Prevention Agency "Measles Response Guidelines (2024)", suspected cases were defined and confirmed using real-time reverse transcription polymerase chain reaction. Data from the National Infectious Disease Surveillance System were used to construct an epidemic curve, calculate serial intervals and attack rates, and evaluate measles-specific immunoglobulin G (IgG) seropositivity using an enzyme-linked immunosorbent assay among 334 healthcare workers from 12 hospitals.

Nine confirmed cases were identified, with up to four generations of transmission. The primary case was an unvaccinated child from a multicultural family with a travel history to Vietnam, and subsequent infections occurred among healthcare workers and caregivers. The overall IgG seropositivity among healthcare workers was 80.2%, with the lowest (64.0%) observed in the 25-34-year age group. Active isolation and surveillance successfully prevented community transmission.

This outbreak highlights the potential for imported measles to spread within healthcare facilities. Strengthened vaccination management for multicultural families and travelers, early recognition and isolation in hospitals, and regular monitoring of healthcare workers' immunity are crucial to preventing future outbreaks.